Study of failed Oxford medial unicompartmental knee replacements at the Royal Cornwall Hospital. Objective. we set up a retrospective study to identify the various reasons for failure of oxford medial unicompartmental knee replacements and to assess their outcome following revision. Materials and Method. Over 5 years (2006- 2010) we identified 26 failed unicompartmental knee replacements, which were revised at the Royal Cornwall hospital. We retrospectively analysed the data to include pre-operative and post-operative Oxford score, range of movement, patient satisfaction and the type of implant used. Results. There were 9 males and 17 females in our series with an average age of 65 years (49 to 80). The average follow up was 2.6 years (1 - 4.6 years). The pre-revision Oxford score was 21.3 (12 to 35), which improved to 41.7 (18 to 47) following surgery. Almost all patients benefited with increase in the range of movement. The implants were revised at an average duration of 4 years and 8 months (1 to 17 yrs) following the index operation. The commonest cause of failure was progression of arthritis in the lateral compartment 50 % (13/26), revision for unexplained pain 23 % (6/26) and aseptic loosening 23 % (6/26). There was one case of sepsis 4 % (1/26). We did not come across dislocation of the bearing. The implants were revised using primary or complex primary knee systems. The infected knee was revised using a two-stage technique. Conclusion. Unicompartmental knee replacement is a successful procedure for treating isolated medial compartment arthritis. Commonest indication for revision in our study was progression of arthritis in the lateral compartment. Revision is relatively easy and results of revision are good with high patient satisfaction. Our results are comparable to published data from larger centres

Objectives

Unicompartmental knee arthroplasty (UKA) is a demanding procedure, with tibial component subsidence or pain from high tibial strain being potential causes of revision. The optimal position in terms of load transfer has not been documented for lateral UKA. Our aim was to determine the effect of tibial component position on proximal tibial strain.